Prior to the past twenty years, dental handpieces, commonly known as drills, operated at a speed of around 8000 to 10,000 rpm and no cooling of such drilling operation existed to any substantial extent. Dental cuspidors also were stationary at one side of the dental chair and flushing water for the same was connected to the office water system and usually employed a continuous stream of water. The only water that usually entered the patient's mouth up to that time was what the dentist squirted into the mouth by way of a syringe for purposes of flushing material removed by the dental handpiece and otherwise.
With the advent of so-called high speed dentistry about twenty years ago, which included the use of so-called dental drills that operated at speeds of 400,000 rpm or more, it was found to be desirable and even necessary to accompany such drilling with a spray of water that continuously flushed the material removed from teeth and the like by the dental handpiece. The amount of water thus discharged required the development of apparatus to rapidly remove the water and debris from the oral cavity and this gave rise to the advent of so-called high-volume evacuation. At that time, however, dental cuspidors of the aforementioned conventional type remained in use and even at present, many dental operatories still employ the same. In addition, saliva ejectors have been used for many years and are still used at present for purposes of removing emissions from the salivary glands which occurs during the time a dentist is working in the oral cavity and vacuum means were, and are, still used to operate such saliva ejectors.
For purposes of providing vacuum in the aforementioned high-volume evacuators and saliva ejectors, as well as certain new forms of cuspidors which are hand-held by the patient, and from which expectoration is removed by vacuum, it has been somewhat common practice to employ mechanism such as the equivalent of pot-type vacuum cleaners, which developed adequate vacuum to satisfy the needs of a limited amount of high-volume evacuators, saliva ejectors and cuspidors in dental offices, particularly if only a single or possibly two operatories were involved.
The modern tendency is for even a single dentist and certainly two or three associated dentists to utilize in many instances, a substantial number of operatories, such as of the order of four to six, or more, particularly where two or more dentists operate in the same suite of offices. To provide adequate evacuation for such an arrangement and number of offices and operatories, more effective means than the capabilities of the pot-type vacuum cleaners to provide vacuum service, now are required.
By way of illustration of evacuation apparatus of the type employing pot-type vacuum cleaner units or the like, attention is directed to prior U.S. Pat. Nos. 2,784,717 to Thompson, dated Mar. 12, 1957, and 3,138,837 to Bishop, dated June 30, 1964. For providing more effective evacuation and capable of being produced by such devices, some evacuating systems including the use of liquid seal pumps were devised and an early example of this type of pump in an oral vacuum system comprises the subject matter of prior U.S. Pat. No. 3,482,313 to Stram, dated Dec. 9, 1969, in which a single liquid seal pump is employed for purposes of supplying vacuum to a high-volume evacuator, a saliva ejector, and a dental cuspidor of the hand-held type, which cuspidor also is provided with flushing water, the removal of which likewise is required by the vacuum system. In said systems, fresh water from the city supply, for example, is continuously fed to the vacuum pump for purposes of maintaining the liquid seal therein that is essential to the effective operation thereof, the water then passing from the pump to a sewer connection. In some installations resulting from the development of said Stram patent, evacuation systems, including a plurality of such liquid seal pumps, have been developed to provide a greater amount of vacuum power, such as the plurality of pumps included in the system comprising the subject matter of prior U.S. Pat. No. 3,964,112 to Plowman, dated June 22, 1976. It readily can be visualized that in systems employing plural pumps of the type referred to require the use of very substantial quantities of water during a single day, for example, and situations are quite common where anywhere from 25 to 90 gallons per hour are known, especially where a number of high-volume evacuators are employed and the water is discharged directly to sewer means from said pumps.
In order to economize in such consumption rates of water, previous efforts have been made to provide evacuating systems with liquid conduit circuitry, filter means, sediment tanks, pressure tanks requiring auxiliary pumps to circulate the liquid, and other control means, several examples of which respectively are shown in said aforementioned Plowman patent, as well as prior U.S. Pat. No. 3,842,448 to Kahn et al., dated Oct. 22, 1974. In both of these prior patents, the evacuating system primarily is concerned with removing the discharge from cuspidors of the type employing flushing water and in order to recycle the waste liquid, it was necessary to include in the system employed in said aforementioned patents, means by which blood, tooth and bone chips, and other extraneous waste material are removed from the fluid which is to be recycled through the cuspidors, said systems even requiring deodorizing means in order that the water recycled to the cuspidors would not have objectionable odors, either to the patient or the professional personnel in the operatory.
It has been found that even more effective systems are desirable, however, not only to provide greater vacuum service but even greater efficiency in recycling the waste water and utilizing even more stringent requirements of fresh water to be supplied to the system, such as of the order of consuming only 25 or 30 gallons per day, as compared with 25 to 90 gallons per hour in the old systems employing, for example, air type blowers, and earlier water pump systems, to provide the vacuum. The present invention provides such more effective and efficient system, details of which are described hereinafter.